constaccess.php

<?php

class Foo {
	const NUM_FOOS = 42;
}

class Bar {
	public $foo;

	function __construct() {

		$this->foo = new Foo();

		$f = $this->foo;
		echo $f::NUM_FOOS;                // Works

		//echo $this->foo::NUM_FOOS;      // Parse error
		//echo $this->getFoo()::NUM_FOOS; // Parse error
	}

	function getFoo() {
		return $this->foo;
	}
}

$b = new Bar();